Problem: Constraints

* H is an integer between 2 and 50 (inclusive).
* W is an integer between 2 and 50 (inclusive).
* s_{i, j} is `.` or `#` (1 \leq i \leq H, 1 \leq j \leq W).
* s_{1, 1} and s_{H, W} are `.`.

Input

Input is given from Standard Input in the following format:


H W
s_{1, 1}s_{1, 2}s_{1, 3} ... s_{1, W}
s_{2, 1}s_{2, 2}s_{2, 3} ... s_{2, W}
:   :
s_{H, 1}s_{H, 2}s_{H, 3} ... s_{H, W}


Output

Print the maximum possible score that Snuke can achieve, or print -1 if the game cannot be completed.

Examples

Input

3 3
..#
#..
...


Output

2


Input

3 3
..#
..
...


Output

2


Input

10 37
.....................................
...#...####...####..###...###...###..
..#.#..#...#.##....#...#.#...#.#...#.
..#.#..#...#.#.....#...#.#...#.#...#.
.#...#.#..##.#.....#...#.#.###.#.###.
.#####.####..#.....#...#..##....##...
.#...#.#...#.#.....#...#.#...#.#...#.
.#...#.#...#.##....#...#.#...#.#...#.
.#...#.####...####..###...###...###..
.....................................


Output

209

Solution (in CPP):

Solution:
#include <bits/stdc++.h>
using namespace std;
int main(void){
    int xv[]={1,0,-1,0},yv[]={0,-1,0,1};
    int r,c,x,y,b=0;
    char in;
    cin>>r>>c;
    vector<vector<int>> tl(r+2,vector<int>(c+2,-1));
    for(int i=0;i<r;i++){
        for(int j=0;j<c;j++){
            cin>>in;
            if(in=='.')tl[i+1][j+1]=9999999;
            else b++;
        }
    }
    queue<pair<int,int>> q;
    if(tl[1][1]==9999999){
        q.push(make_pair(1,1));
        tl[1][1]=1;
    }
    while(!q.empty()){
        y=q.front().first;
        x=q.front().second;
        q.pop();
        for(int i=0;i<4;i++){
            if(tl[y+yv[i]][x+xv[i]]!=-1&&tl[y][x]+1<tl[y+yv[i]][x+xv[i]]){
                tl[y+yv[i]][x+xv[i]]=tl[y][x]+1;
                q.push(make_pair(y+yv[i],x+xv[i]));
            }
        }
    }
    if(tl[r][c]==9999999)cout<<-1<<endl;
    else{
        cout<<r*c-tl[r][c]-b<<endl;;
    }
}